The Study Of Mussel Adductor Muscle-shell Interface Structure And Bonding Mechanism

The mussel adductor muscle scar (AMS) is the fixation point of adductor muscle to the shell. It is an important organic-inorganic interface and stress distribution area. The scar is the most important stress distribution site in the mussel, it has a similar structure to the tendon-bone connection site. Despite recent advances, our understanding of the structure and composition of the AMS remain limited. The structure and organic matrix of the scar in Mytilus coruscus are investigated. The scar is found to be a hierarchically multilayered structure composed of organic matrix and structurally different minerals. At Mytilus coruscus AMS position of columnar layer and nacre, with the presence of small amounts of calcite, aragonite is its main form of calcium carbonate mineral.This consistents with the mussel Mytilus galloprovincialis experimental results, but the aragonite relative content is slightly different. Study of the organic matrix shows that there is at least one protein that seemed to be preferentially localized in this columnar layer. Additionally, we report our study on the AMS of three bivalves:Mytilus coruscus, Chlamysfarreri and Ruditapes philippinarum. Results show that there are significant differences among their AMS structures. A columnar layer is found above the nacreous platelet shell structure at the AMS in both Mytilus coruscus and Chlamys farreri and this layer is more organized in the AMS of Mytilus coruscus through SEM. AFM results show that the AMS is much smoother than the nacreous inner shell in all the three species. FT-IR and XRD indicate the AMS column layer has minor different compositions from the nacreous shell layer. Both of them are mainly composed of aragonite, but there is a higher content at the AMS columnar layer. SDS-PAGE study of the proteins isolated indicates that there is a 70 kDa protein which seemed to be specifically located to the highly organized columnar AMS structure in Mytilus coruscus.We are carrying on the exploration of the 70 kDa protein purification methods. The main method is to use the 8 M urea solution to treat the shell powder, after that, we use a high pressure liquid chromatography (HPLC) to purify protein further. The protein purification effect of C8 reversed phase chromatographic column is much better than the other columns, the 70 kDa and 100 kDa protein can be isolated from a variety of protein. Similar characteristic is found in these two kinds of protein, many kinds of chromatographic column are difficultly used to purify them. In the end. we take the method of gel eluttion to obtain pure 70 kDa protein.Further analysis of this protein showes it rich in Asx (Asp+Asn), Glx (Glu+Gln) and Gly. Its protein gel sample analysis result shows a very close relationship between the 70 kDa specificity protein and two kinds of mussels genes (>gi|XXXXX|comp269280_c1_seq1 orf=823-3420(-) and >gi|XXXXX|comp267300_c0_seql orf=2-1066(-)). In the process of protein purification, there is similar characteristic between 70 kDa and 100 kDa protein so that we have difficulty to purify. We should take some more research in the gene >gi|XXXXX|comp269280_c1_seql orf=823-3420(-).The adhesion propertiy and other properties of the specific 70 kDa protein at the adductor muscle-shell interface has yet to be further explored, but we can confirm that the protein plays an important role in organic-inorganic interface adhesion. Some researches for mussel foot protein related adhesive can provide some reference and inspiration for our experiment. The special structure and composition of the AMS might play an important role in the stability, adhesion and function at this stress distribution site.